46 



Animal Life by the Sea-shore. 



FIG. 49. OPOSSUM SHRIMP (AFTER BELL) 



for its regeneration from tlie base, the tissues of which are 

 conformed for the purpose. 



The most niteresting members of the Anomura are un- 

 doubtedly the Hermit Crabs, represented by several species on our 

 coasts (Fig. 48). Eiipagurus bernhardus is the largest and 

 commonest. The abdomen is imperfectly segmented and devoid 



of armour, 

 thus necessi- 

 tating protec- 

 tion, for which 

 purpose the 

 emptj? shell of 

 a mollusc is 

 selected. The 

 appendages of 

 the abdomen 

 are in a re- 

 duced condi- 

 tion, and the 



last pair, instead of forming a tail-fin, is modified into a special 

 organ which helps the animal to fasten itself to the deeper recess 

 of the shell. The last two pairs of walking-legs are reduced, 

 but the pincers are well developed and of unequal size, the 

 right being the larger and serving as an operculum to cover 

 the mouth of the shell when the hermit withdraAvs into his 

 dweUing, as shown on the right hand of Fig. 50. Eiipagurus 

 bernhardus grows to a length of about five inches, and, in the 

 adult state, requires the shell of a whelk ; j'ounger specimens, 

 most frequently met with in rock-pools, select smaller shells, 

 such as those of the winkle, the Trochus or the screw-shell. 



Although the Decapods include the more conspicuous 

 forms, members of this division represent but a very small 

 proportion of the Crustaceans of our shores. The representa- 

 tives of the less highly organised divisions are for the most part 

 of very small size and, therefore, escape attention from the more 

 superficial observer. The Crustaceans which come nearest 

 to the Decapods are those known as Schizopoda, of which Mysis 

 flexuosa, the Opossum Shrimp, is a common representatn'e, found 

 in abundance in sandy pools at low tide (Fig. 49). Mysis has the 

 general appearance of a small shrimp, but is easily recognised 

 by the number and structure of the appendages below the 

 carapace ; there are no walking-legs, their place being taken 

 by seven pairs of biramous swimming legs. During the breeding 

 season, the females carry their eggs in a kind of brood-pouch 



